Viñas hit .557 as a senior at Miami American High School and was selected in the 33rd round of the 1991 Major League amateur draft by the Chicago White Sox. He debuted with the Gulf Coast League's GCL White Sox as a first baseman. In 1992 he played both first base and catcher for the Utica Blue Sox of the Class A New York-Penn League and the South Bend White Sox of the Midwest League. He stayed with South Bend as a full-time catcher in 1993 and also played that year with the Florida League's Sarasota White Sox, where he set career highs with 68 runs and 43 walks.

With Birmingham Barons, Viñas was a backup to starting catcher Scott Vollmer. That year he batted .269 with 47 runs on 100 hits, 61 RBI and 6 home runs. Viñas was promoted to the Nashville Sounds of the AAA American Association and later traded to the Baltimore Orioles. He got time as a designated hitter for the Rochester Red Wings of the AAA International League in 1998 and played his best season there in 1999 with 20 home runs and 83 RBI. In 2000 Viñas was traded to the Cleveland Indians and debuted with the Akron Aeros, later playing for the Pawtucket Red Sox as a member of the Boston organization. He returned to Rochester before ending his playing career after the 2001 season.

From 2002 to 2009 Viñas coached in the Baltimore Orioles system, including five as the organization's hitting coordinator. He spent 2010 as a coach with the GCL Yankees. In 2011 the White Sox hired him to manage the WInston-Salem Dash and he compiled a 69-71 record in the Carolina League. In 2012, as manager of the Single-A Kannapolis Intimidators, Viñas went 61-78. In December of that year he was named the 67th manager of the Birmingham Barons.

Viñas' first Barons team was also the first to play at Regions Field in downtown Birmingham. That team barreled its way through the first half of the season, going 44-26, nine games ahead of Chattanooga in the Southern League's north division. They finished the season with a 77-63 record. They defeated second-half division leader Tennessee Smokies in the League playoffs and went on to beat the Mobile BayBears in five games to claim the championship.

The next two seasons, the Barons went 60-80 and 69-70. Viñas' overall record over three season in Birmingham was 206-213 (.492). In 2016 he was promoted to the AAA Charlotte Knights and succeeded by Ryan Newman. Viñas returned to manage the 2017 team, but was again succeeded by Newman when he was forced to step down for personal reasons.